The present invention relates to a waterproof microphone (hereinbelow abbreviated to a waterproof mike) allowing sufficient sound collection over wider frequency bands in, for example, high-humidity places exposed to rain and fog, high mountains with low pressure and even under water with high pressure.
Conventionally, a condenser-type waterproof mike includes a cylinder-shaped case, a diaphragm and an electrode plate, where the cylinder-shaped case has an anterior wall, and the diaphragm and the electrode plate are disposed in the case in sequence from the anterior wall side toward the rear side. An anterior chamber is formed between the anterior wall and the diaphragm.
As shown in FIG. 9, the anterior wall 102 of the case 101 had an aperture 102a in the center. The aperture 102a was not overlapped with an inner face 110a of the anterior chamber 110 (see U.S. Pat. No. 3,486,151).
Since the conventional waterproof mike was structured such that the aperture 102a was not overlapped with the inner face 110a of the anterior chamber 110 as shown in FIG. 9, moisture such as rain water, if entering the anterior chamber 110, is not easily discharged out of the case 101 but remained in the anterior chamber 110. The moisture in the anterior chamber 110 is kept in contact with the diaphragm 120, which causes considerable attenuation of sound pressure collected by the diaphragm. As a result, sufficient sound collection is disadvantageously disturbed.